This article describes light bar wiring for correct and compliant flashing operation.
In the U.S., RRFB light bar fixtures are required to comply with Federal Highways, MUTCD, IA-21.
The left-hand-side of the light bar must flash first on initiation of the flashing sequence for MUTCD compliance.
For all Carmanah RRFB light bars, this means connecting the WHITE and BLACK wires from the light bar harness to the left-hand side RRFB indication – as you face the light bar.
For instances when light bars have been pre-wired, ensure that this orientation is maintained when mounting the light bar assembly to the post or pole.
See image below: